1. Field of the Invention
The present invention relates to an external door handle, particularly for vehicles which when actuated acts through a connecting member on a lock. The handle includes a crash locking means for the connecting member, wherein the crash locking means is normally inactive. A crash sensor reacting to inertia forces renders the crash locking means active when a crash occurs. As a result, the crash locking means blocks the connecting means and an inertia force which acts on the handle as a result of the crash to actuate the handle is not transmitted to the lock.
2. Description of the Related Art
When the handle of a vehicle is actuated, a connecting member acts on a lock. In the event of a crash, inertia forces act on the handle and the members connected to the handle. These inertia forces may have the result that the handle carries out an undesirable actuating movement and opens the lock as a result. This causes the door to open and the passengers sitting in the vehicle could be ejected from the vehicle. Crash locking means are used to prevent this.
Such crash locking means act on the connecting member, but they are normally inactive. However, a crash sensor exists which reacts to inertia forces and makes the crash locking means active in the case of a crash. In that case, the connecting member is blocked and an actuation of the handle remains inactive.
It is known from DE 199 10 328 A1 to use a cylinder/piston unit between an external door handle and a connecting member which acts on a lock. A liquid is arranged in the cylinder and the piston has through openings which normally are held open by a blocking member, such as a sealing disk. When the door handle or the connecting member is initially quickly adjusted as the result of an accident, the piston is slightly moved in the liquid. The resulting flow of the liquid between the two chambers in the cylinder separated by the piston causes an at least slight pressure increase in one of the chambers, so that the blocking element closes the through opening. Any further movement of the piston in the cylinder is now no longer supposed to be possible. This known crash locking means is not operationally safe. The adjustment of the sensor in the interior of the cylinder to the correct reaction value is difficult.
Such crash locking means are usually constructed as a so-called xe2x80x9cmass locking meansxe2x80x9d. For example, in an external door handle constructed as a pull handle and known from DE 20 23 859 B2, an additional mass acts on the shaft of the handle which serves as a connecting member. The additional mass is mounted on one arm of a two-arm lever and is biased by a tension spring which ensures that the arm of the lever normally engages behind a projection of the shaft. In the case of a normal actuation of the handle, this spring load is usually overcome, so that the lever releases the projection at the handle shaft. However, in the case of a crash, such a high inertia force acts on the additional mass that the other lever arm holds the projection and, thus, prevents an actuation of the handle resulting from an inertia force. Also, mass locking means interfere with the normal operation of the door handle.
It is also known in the art from DE 199 24 685 A1 to use between a latch and an actuating lever a switchable coupling which operates with an electrorheological liquid. The axis of the actuating lever is fixedly connected to a rotary cylinder which is located in a hollow cylinder. The hollow cylinder, in turn, is fixedly connected to the latch. The electrorheological liquid is located in the free space between the rotary cylinder and the hollow cylinder, where the electrodes for producing an electrical field are also located. In dependence on the electrical field, the liquid changes from a low viscous state through the plastic state to a solid state. When the liquid solidifies, the coupling is active and when the actuating lever is turned, the latch is also moved. The use of a crash sensor for controlling the state of aggregation of the liquid is not provided.
Finally, it is also known in the art from DE 197 54 167 A1 to use an electrorheological liquid for blocking a component which can be pivoted about an axis, for example, a door which is to be opened by a certain angle and then locked. A position sensor determines the respective angle position of the door and the position is made available to an electronic evaluation unit. The electronic evaluation unit compares the actual position of the door with the intended position and acts on an electronic control unit which controls the state of aggregation of the liquid through electrodes which are arranged on a rotary piston, on the one hand, and on a fixed cylinder, on the other hand. The rotary piston is fixedly connected to the door. Once the desired pivoting position of the door has been reached, the electrorheological liquid changes into its solid state which leads to locking of the door in the angle position. The use in connection with crash locking means is not provided.
Therefore, it is the primary object of the present invention to develop an external door handle of the type described above which avoids the disadvantages of the known crash locking means.
In accordance with the present invention, the connecting member of the door handle has a drive member which is movable with the connecting member. The drive member is arranged in a liquid medium and moves in this medium when the connecting member is actuated. The viscosity of the medium is changeable in dependence on an electrical field acting on the medium. The crash sensor controls the electrical field prevailing in the medium.
The crash locking means according to the invention operates in accordance with a principle which is completely different and novel as compared to the known crash locking means. In the event of a crash, the invention only changes the viscosity of the liquid medium. Such media are called xe2x80x9cSKS-intelligent materialsxe2x80x9d. This medium changes its viscosity in dependence on an electrical voltage, i.e., in dependence on an electrical field prevailing in the medium. The medium is normally highly liquid and permits an easy movement of the drive member in the medium when the handle is actuated. The remaining flow resistance of the medium can even be usefully utilized for damping the actuation of the handle. This is of interest in case of door handles which are subject to a restoring force and which are supposed to move back into their initial positions as noiselessly as possible. In this connection, a principle can be utilized which is known from the very different field of xe2x80x9cdoor closersxe2x80x9d, in which the actuation of the handle is to be easy and smooth, but its return movement is to be dampened by suitable valves or labyrinths.
However, the gist of the invention resides in applying in the event of a crash an electrical field to the medium which is so high that a movement of the drive member in the medium is essentially blocked. It is sufficient for this purpose to provide a sensor which responds to inertia forces and actuates an electrical switch for an electrical field to be produced in the medium. The drive member and the medium can be located at any selected location in the chain of elements between the handle and the lock. Moreover, the crash sensor can also assume other functions, for example, transmitting an alarm of the accident through radio or the like to monitoring stations located outside of the vehicle.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.